344 THE HOLARCTIC REGION. [CHAP. 



the case with the musk-ox (Ovibos), but as this animal ranged over 

 Europe and northern Asia during the Plistocene, it can scarcely be 

 regarded as distinctive of the western area. Of other peculiar 

 New World ungulates, the prong-buck (Antilocapra) and certain 

 deer of the genus Cariacus are found within the Holarctic region, 

 but the former seems to be essentially a Sonoran type, while the 

 latter, although probably also of Sonoran origin, occurs through 

 Central and South America. 



The Tertiary genera of mammals peculiar to North America 

 may be best considered in the chapter devoted to the Sonoran 

 region, to which they for the most part belong ; and this portion 

 of the subject may be accordingly concluded by tabulating the 

 existing genera or groups peculiar to the area under consideration. 

 These will stand as follows, viz. : 



Insectivora. 



SORICID.E. Sorex. The sub-genus or genus Neosorex. 

 TALPID^E. Condylura. 



Rodentia. 



HAPLODONTIDJE. Haplodon. 

 MURID^:. Phenacomys. 



Synaptomys. Confined to the southern 

 portion of the area. 



Fiber. Enters Sonoran. 

 DIPODID^E. Zapus. 



HYSTRICID.E. Erethizon. 



Ungulata. 



BOVID^E. Haploceros. 



Even if we add to the above certain other sub-generic types, 

 such as the spruce-squirrels (Tamiasdurus) and the bushy-tailed 

 wood-rats (Teonoma), and likewise take into account the number 

 of Old World types (in many cases widely-distributed ones) that 

 are absent, it can scarcely be urged that such an assemblage is 

 sufficient to constitute a zoological region by itself. Those of my 

 readers desirous of consulting lists of the species inhabiting the 

 Arctic and Boreal zones of Dr Merriam, will find them in his 

 memoir 1 . 



1 Appendix, No. 19, pp. 24, 25. 



